This invention relates to a fabric softening composition and to a particulate laundering product including the softener.
A fabric softener is a dilute solution or dispersion of a quaternary ammonium derivative used to treat fabrics in the final rinse of a laundering process in order to make the fabrics feel softer. In addition to softness, fabric softeners are known to also provide static control. Because of the affinity of quaternary ammonium compounds for negatively charged surfaces, their single largest market has been as fabric softeners. Commercial fabric softeners generally include about a four to eight percent dispersion of quaternary ammonium compound which is added to the rinse cycle of the washing process. The quaternary ammonium compound can also be applied to a nonwoven sheet or a polyurethane foam which is added with wet clothes in a dryer. Such sheets contain a fatty acid ester which allows the quaternary ammonium compound to transfer from the sheet to the clothes in the dryer during the drying cycle. Recently, there have been devised combined detergent and softener formulations which allow introduction of all additives in the wash cycle.
Modern washing machines work automtically and the operator places the laundry in the machine, pours in the detergent, and sets the controls. One set of controls determines whether the machine employs hot, warm, or cold water. Water enters the machine through hoses connected to the hot and cold water pipes. The operator also sets controls in order to select the length of washing and rinsing time, and the amount of water that enters the machine. The machine is powered by an electric motor and includes a filter that removes lint, and automatic dispensers for bleach and fabric softeners. A wash cycle typically includes four stages. In the wash cycle, after water fills the wash tub, an agitator reverses direction alternately and moves the laundry through the water and detergent, and forces water through the items of laundry. The washer is then emptied of all of the wash liquor in the spin cycle and the clothes are spun to remove excess water. In the rinse cycle, clean water is added along with the fabric softener and the clothes are again agitated. The washer is emptied of rinse liquor and the clothes are spun in a final spin cycle during which time excess water is removed and pumped out of the machine through a drain hose. The clothing is then ready to be removed from the machine and dried in a dryer or hung on a clothesline until dry.
Fabric softeners for use in such machines are well known in the art. For example, in British Patent No. 1,549,180, issued July 25, 1979, Dumbrell et al disclose a fabric softener which includes, in addition to the softening benefit, the additional benefits of easier ironing, antistatic properties, pleasanter feel, and soil release properties. The additional benefits are stated to be derived from the inclusion along with a cationic quaternary ammonium fabric softening agent, of a silicone compound which is said to be an aqueous emulsion of a linear siloxane.
Specifically, Dumbrell et al relate to fabric softening compositions that include an aqueous dispersion of a cationic softening compound, and a silicone emulsion. The cationic compound is disclosed to be one or more or mixtures of a combination of quaternary mono-ammonium compounds such as tallowtimethylammonium chloride, and ditetradecyldimethylammonium chloride; quaternary imidazolinium compounds; polyammonium compounds such as acid salts of diamine compounds, and polyamine salts; and polyalkyleneimine salts. The silicone emulsion is preferably a linear dialkyl or alkylaryl siloxane which may be partially or wholly fluorinated, or substituted with cationic nitrogen groups. The viscosity is disclosed to be, at twenty-five degrees Centigrade, at least one hundred and up to eight thousand centistokes. The weight ratio of siloxane content of the emulsion to the dispersion is five to one, to one to one-hundred. Representative compositions are said to be cationic emulsion polymerized dimethylsiloxanes, with the emulsifying agent being, for example, ditallowyldimethylammonium chloride; quaternized polysiloxanes such as dipyridinium poldimethylsiloxane; and aminofunctional linear polysiloxanes such as polydimethylsiloxanes containing dimethylaminopropyl groups.
A basic distinction should be drawn between a rinse cycle softener and a wash cycle softener. As noted hereinabove, the rinse cycle fabric softener is a liquid dispersion of a quaternary ammonium compund which is added separately to the rinse liquor during the rinse cycle of the laundering device. A powdered wash cycle fabric softener on the other hand is typically in the form of solid particles of the quaternary ammonium compound which are mixed in with the powdered laundry detergent and added to the wash liquor by the homemaker, for example, before initiation of the wash cycle of the fabric laundering device.
Dumbrell et al noted previously relate to the rinse cycle type of fabric softening formulation. Typical of the wash cycle fabric softening variety of product is disclosed in U.S. Pat. No. 4,741,842, issued May 3, 1988, to Adams. In Adams there is described a particulate detergent of an anionic surfactant, a builder salt, and a mixture of a cationic amine softener such as a quaternary ammonium compound and an ethoxylated tertiary amine. The function of the ethoxylated tertiary amine is said to be as a dispersant-softener.
In accordance with the present invention, what has been achieved is that a viable alternative has been discovered for the ethoxylated tertiary amine of Adams in the nature of a particular combination of at least two silicone materials. Thus, a silicone polymer and a silicone copolymer have been combined and substituted for the ethoxylated tertiary amine of Adams. It has been found that such combination disperses the fabric softener active, in both cases the quaternary ammonium compound, and provides an improved delivery of the active component of the softener formulation to the fabrics being treated, with the result that there is provided better softening together with a more pronounced reduction in static. The reduction in static provided by the silicone compounds of the present invention is based on the fact that the fibers of the fabrics are lubricated by the compounds of the present invention with the result that less static is generated. The silicone polymer and the silicone copolymer combination also disperses the active softener component of the formulation to a degree at least equal to or in excess of the ethoxylated tertiary amine (ETA) of Adams since the silicone combination coats the individual particles of the quaternary ammonium compound active component of the wash cycle fabric softener formulation, so that in the wash cycle, the agglomerates of the active component disperse apart one from the other, thus freeing these individual particles to deposit themselves throughout the fabric in a more uniform pattern. Since the fabrics carry a negative charge, the positively charged active component particles are attached thereto. When the fabrics are added to a dryer at the end of the wash cycle, these individual particles are enabled to deposit, melt and spread to a more uniform degree with the silicone combination, providing softer clothes and less static because of the waxy quality of the active component attributed to the clothing or fabrics.
Thus, the concept of the present invention provides new features, benefits and advantages, not taught in the prior art.